A record-breaking storm drenched Toronto July 9, causing flashfloods, forcing the closure of three subway lines, and leavingresidents stranded in their cars or without power in theirhomes.

In one incident, police and firemen worked seven hours to rescue1,400 commuters from a waterlogged train, finally getting theevacuees to dry ground in inflatable boats.

The squall was caused by two separate storm cells that loiteredover Canada's largest city for hours. International news sources say that Pearson International Airport receivednearly 5 inches of rain in four hours July 8, breakingthe previous single-day rainfall record set by a hurricane in1954.

According to Reuters, about 300,000 customers of the city's main electricalutility, Toronto Hydro, lost power on Monday because thetransmission stations were under 20 to 30 feet of water. 70,000people were still without electricity on Tuesday.

AIR says that Canada's thunderstorm season typically begins inlate May or early June, when the warm daytime surface temperaturesand humidity needed for convective storms is strongest. A jetstream currently positioned over the northern plains of the UnitedStates and Central Canada is presenting a threat for hail,tornadoes, and straight-line winds. Southeastern Ontario andsouthern Quebec, where Toronto is located, are at especially highrisk of severe summer storms.

Two weeks ago, flooding in Calgary (which is west of Quebec)caused the evacuation of 100,000 people; three werekilled.

Floodwaters are beginning to recede in some areas of Toronto,but AIR says there is no indication yet of the number of homes andbusinesses damaged; however, the modeler expects many claims to beattributable to sewer backup, a typical optional coverage onstandard residential policies.